I'm on my 3rd set of Anakee 3 tires. I cannot fault the rears - as others have said the front on the other hand wear funny and only last 1/2 the distance to the rear.`
I run my rear pressure at 40-42psi.
I've ridden even when the pressure was in low at 30-32 and no shimmey shimmey - but do check your tire pressures.
I can only fault the road surface... changes in tar surfaces / repatched areas / edges / tar snakes / grooves / cracks in road surface in corners - I have hit a few of these and had some mid corner diamond producing moments!
Tar snakes are the worst!!!
If the rear end shimmey is consistent this might mean a mechanical issue like TABASCO has pointed out with swing arm being torqued causing a twist on the axel, even loose rear wheel spokes.